Create isStagingDeployLocked action

.github/actions/isStagingDeployLocked/action.yml

@@ -0,0 +1,12 @@
+name: 'Check if the StagingDeployCash is locked'
+description: 'Checks if the open StagingDeployCash issue has the LockCashDeploys label'
+inputs:
+    GITHUB_TOKEN:
+        description: Auth token for Expensify.cash Github
+        required: true
+outputs:
+    IS_LOCKED:
+        description: Whether or not the open StagingDeployCash issue is locked.
+runs:
+    using: 'node12'
+    main: 'index.js'